[Effect of DMBA and benz (alpha) anthracene on the biogenic amine level in the rat brain]

Thirty minutes after the administration of DMBA (5 mg i. v.) to rats the level of norepinephrine, dopamine, serotonine (5-HT) and 5-IIIAA in the hypothalamus was decreased, while monoamines levels in the brain stem and hemispheres was unchanged. After benz(a) anthracene (5 mg i.v.) treatment the level of 5-HT in rat hypothalamus was decreased, but catecholamines and 5-HIAA levels were not changed. Pretreatment with L-DOPA abolished the elevation of the threshold of hypothalamic sensitivity to estrogen suppression, induced by 20-methylcholanthrene in rats, and alpha-methyl-DOPA enhanced. It is suggested that the central (hypothalamic) mechanisms participate in the release of the carcinogenic effect of polycylic hydrocarbons in rats.